In telecommunication systems, typically a transceiver sends a signal having a predetermined frequency and phase. When represented in the complex plane, the signal is a phasor having both phase angle and frequency. The phasor rotates around the axis with time. During transmission the signal is corrupted by several factors, such as transmission through a noisy channel, and interference from other users, etc.
Upon receiving the corrupted signal, the receiver must then extract the original information. This process may involve any number of steps, where the signal is manipulated both in phase and frequency. The process of estimating the true phase and frequency of the corrupted signal is referred to as channel estimation. Channel estimation has two (2) basic classes: coherent and non-coherent.
Non-coherent estimation estimates the signal without determining the phase angle θ. It tends to be less costly, but offers poor performance compared to the coherent method.
In contrast, coherent estimation requires estimates of both phase angle, θ, and frequency offset. These methods offer good performance, where the bit error probability is low compared to the non-coherent methods, but tend to be more costly.
Because of technological advancements, communication channels are being designed to transmit more and more data. For instance, wireless systems are being designed which accommodate the transmission of computational data, so that internet browsing or computer networking will be possible via a wireless connection. A need exists therefore for a quicker and more accurate method of channel estimation consistent with new technologies of transmission.